The report was to be released Friday by Sen. Carl Levin, D-Mich., chairman of the Armed Services committee, the Washington Post reported.
Feith was undersecretary of defense and one of the Pentagon's policy chiefs until he left the Bush administration in 2005.
The Pentagon inspector general said Feith relied on "reporting of dubious quality or reliability" in 2002 as the administration prepared to invade Iraq. His office was "was predisposed to finding a significant relationship" between Iraq and al-Qaida, the inspector general's reported said.
Feith, in a telephone interview with the Post, suggested that his actions were being misconstrued.
"This was not 'alternative intelligence assessment,'" he said. "It was from the start a criticism of the consensus of the intelligence community, and in presenting it I was not endorsing its substance."